Fuse construction



Feb. 25, 1958 G R. MCCLOUD FUSE CONSTRUCTION 2 Sheets$heet 1 Filed Feb. 25, 1955 D u 0 K0 we M E V m E 6 R O E 2 G ATTORNEY Feb. 25, 1958 FUSE CONSTRUCTION Filed Feb. 25, 1955 2 Sheets-Sheet 2 3'7 Fl a. Z

Z l \5 w INVENTOR.

GEORGE R. MCwuo A-r-roauav G. R. MCCLOUD 2,824,927

United States Patent FUSE CONSTRUCTION George R. McCloud, Cudahy, Wis., assignor to McGraw- Edison Company, a corporation of Delaware Application February 25, 1955, Serial No. 490,465

6 Claims. (Cl. 200114) This invention relates to a circuit interrupter of the expulsion fuse type.

In circuit interrupters of the type hereinab-ove mentioned, such as that shown in the patent to W. O. Schultz et al., No. 2,310,466, of February 9, 1943, for Fuse Construction, assigned by mesne assignment to the same assignee as the present invention, an expulsion fuse of the drop out type was provided and was associated with a manually operable lever, such as one capable of opera tion through the medium of a switch stick, and so arranged that when it was desired to open the circuit manually, force was applied to the lever to cause mechanical rupture of the fuse link at its weakest point. Thereafter, expulsion action took place and the fuse tube was cleared. Also, under normal conditions when an overload occurred, the expulsion fuse would operate in the customary manner and rupture under overload and clear itself.

In devices of this type it was found that when force was applied through the agency of a switch stick for instance, to open the circuit under load as described hereinabove, that there was a tendency to separate the movable contact of the drop out fuse assembly from the stationary upper contact of the support prior to the time that the fuse was mechanically ruptured. This frequently resulted in burning out or destroying both the movable and stationary upper contacts.

This invention is designed to overcome the above noted defects and yet to retain all of the advantages incident to the type of structure described hereinabove, and a primary object of this invention is to provide a circuit interrupter of the expulsion fuse type and of the drop out type which is so made that when force is mechanically applied through a switch stick, for instance to a lever or other means carried by the fuse tube assembly, that there is no tendency to separate the movable upper contact from the stationary upper contact but instead in which there is a tendency to maintain these contacts closed due to the force applied through the switch stick.

Further objects are to provide a force multiplying mechanism carried by the fuse tube assembly and so arranged that the force or pull applied to times that applied to the switch stick thereby lessening the actual pull on the switch stick and increasing the effective pull on the fuse link itself.

In greater detail, further objects are to provide a cam construction of simple type associated with the switch stick receiving lever and with the fuse extracting lever so as to accomplish the multiplication of forces hereinabove described.

Further objects are to provide a device of the type hereinabove outlined which also will act in the capacity of an ordinary expulsion type drop out fuse when an overload occurs.

A further object is to provide a construction as outlined hereinabove in which an open type eyelet is provided adjacent the upper end of the fuse tube assembly so that the lineman cannot inadvertently open the circuit under load by hooking the switch stick into the upper the fuse link is many 2,824,927 Patented Feb. 25, 1958 a cc open eyelet and thereafter pulling the fuse outwardly to disengage the upper movable contact of the fuse tube assembly from the upper stationary contact of the support, but, nevertheless, to provide a construction so that the fuse tube assembly can be readily placed in service after refusing by using an ordinary switch stick.

Further objects are to provide the novel construction hereinabove set forth which can be used with a standard type of support customarily used with a drop out expulsion type fuse.

An embodiment of the invention is shown in the accompanying drawings in which:

Figure l is a side elevation of the apparatus.

Figure 2 is a view partly in section and partly broken away of the fuse tube assembly removed from the support assembly.

Figure 3 is a sectional view on the line 3-3 of Figure 1.

Figure 4 is a fragmentary view of the lower portion of Figure 2 showing the position of the parts after the fuse extracting lever has been pulled down and before the fuse tube has cleared itself.

Figure 5 is a view looking upwardly from the bottom of Figure 2.

Referring to the drawings it will be seen that the device comprises a support assembly indicated generally by the reference character 1 which is adapted to be attached to any suitable type of support and a fuse tube assembly indicated generally by the reference character 2 and removably carried by the support assembly. The support assembly comprises an insulator 3 which has an attaching bracket 4 and upper and lower contacts 5 and 6.

The upper contact comprises a stationary member 7 and a U-shaped spring contact arm 8 pivoted as indicated at 9 at its transverse portion with the free ends projecting outwardly and looped back to provide upper looped portions ltl bearing against a part of the stationary portion and lower arms 11 provided with shouldered portions 12 behind which the transverse arms 13 of the upper contact 14 of the fuse tube 15 are normally detachably locked. A connector 16 may be carried by one of the lower arms.

The lower stationary contact indicated generally at 6 is provided with a pair of hooked arms 17 which receive trunnions 18 carried by a fuse link extracting lever 19 pivoted at a fixed point to a bracket 20 at the lower end of the fuse tube. The lever 19 is provided with an outwardly projecting threaded pin 21 on which a thumbnut 22 is screwed to thereby provide means for clamping the lower flexible end 23 of the fuse link to the lever 19 through the medium of the gripping member 24.

The lower contact assembly of the fuse tube includes a U-shaped operating or cam lever 25 pivoted at a fixed point as indicated at 26 to the lower collar 27 of the fuse tube 15. The collar 27 is integral with the bracket 20. The bracket 20 is provided with a switch stick receiving eyelet 28 for removing and repositioning the fuse tube in the usual manner. The U-shaped operating lever 25 is provided with a pair of cams 29 on opposite sides which engage the end lip 30 of the fuse link extracting lever 19 of the fuse tube assembly as shown most clearly in Figure 2. The U-shaped operating lever 25 includes a switch stick receiving lever or arm 31 on one side thereof which projects rearwardly with reference to the trunnions 18 and is provided adjacent its outer end with a .switch stick receiving notch 32.

bly but instead tends to rock the fuse tube inwardly and thus does not have any tendency whatsoever to detach the upper movable contact of the fuse tube from the stationary upper contact of the support assembly. This is a very important feature as it prevents any inadvertent detaching of the upper movable contact of the fuse tube from the upper stationary contact of the fuse tube assembly while the fuse link is carrying a load. The fuse link is provided with a weakened fusible portion 33 adjacent its upper end and with an upper disk or top portion 34 which is clamped to the upper contact of the fuse tube by means of a frangible screw cap 35.

From the description thus far given it is apparent that the circuit may be interrupted under load without damage to the parts for when the switch stick is hooked into the notched portion 32 at the outer end of the lever 31 and is pulled downwardly, the cams 29 of the lever 25 coacting with the lip 30 provide a force multiplying means which will rupture the fuse link at its weakest portion 33. The fuse tube immediately clears itself by the usual expulsion action and by the action of the fuse extracting lever 19 and drops downwardly and outwardly away from the upper stationary contact after it has cleared itself.

It is to be noted that there is a slight downward motion allowed the arms 11 of the upper stationary contact which follows the projecting arms 13 of the movable contact of the fuse tube assembly downwardly and maintains electrical connection therewith. The fuse tube drops downwardly a sufiicient distance to detach its upper end from the stationary upper contact and thereafter rocks outwardly in the usual manner. The fuse tube may be readily removed from the stationary support assembly -by hooking the switch stick into the eyelet portion 28 and disengaging the trunnions 18 from the hooks 17. The fuse tube after refusing is replaced by means of the switch stick in the usual way and is rocked into its normal position as shown in Figure 1.

It is to be noted particularly that the upper eyelet consists of the two arms 36 and 37 which provide, in effect, an open eyelet. This in no way interferes with the engagement of the switch stick in the eyelet for rocking the fuse tube back into service or normal position but it precludes withdrawing or rocking of the fuse tube downwardly out of service position while the fuse is carrying a load since the switch stick cannot be hooked into the upper open eyelet for rocking the fuse tube outwardly.

It will be seen that a novel type of fuse construction has been provided by this invention which prevents inadvertent detachment of the upper movable and stationary contacts under load even if an attempt is made by the lineman to rock the fuse tube downwardly through the agency of the switch stick and the upper eyelet 36, 37. it will be seen also that there can be no detaching of the upper movable contact from the upper stationary contact under load when force is applied through the medium of the switch stick to the lever 31, since any force applied in this manner tends to maintain contact between the movable and stationary upper contacts. It is to be noted that the points at which the operating or cam lever 25 and the fuse link extracting lever 19 are pivoted to the lower portion of the fuse tube, are fixed points. This prevents swinging of the switch stick receiving arm 31 out of its correct position and thereby insures the accurate engagement of the cams with the lip 39 of the fuse link extracting lever 19.

It will be seen that a novel type of fuse construction has been provided in which the fuse link can be mechanically manually interrupted under load without damage to any of the parts while at the same time the fuse link is always in readiness to operate in its usual capacity. Under both these conditions, it will be seen that the fuse tube readily clears itself whenever the fuse link is rup tured.

It is also to be particularly noted that when the fuse link is mechanically manually interrupted that there is til) no tendency to separate the upper movable contact from the upper stationary contact.

Although this invention has been described in con siderable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

1 claim:

1. An expulsion fuse construction comprising a support assembly having an upper and a lower stationary contact; and a fuse tube assembly having pivot means pivoted on said support assembly for rocking motion of said fuse tube assembly outwardly from said support assembly, said fuse tube assembly including a fuse tube having an open lower end and an upper movable contact normally engaging the upper stationary contact, a fuse link in said tube electrically connecting the upper movable contact with the lower stationary contact, said pivot mean includ ing a supporting lever pivoted on said fuse tube and on said support assembly, and an opera-ting lever pivoted at a fixed point on said fuse tube assembly and normally operatively associated with said supporting lever for mechanically moving said supporting lever for rupturing said fuse link when said operating lever is rocked downwardly, said operating lever being wholly out of contact with said fuse link at all times and having a free end movable downwardly when force is applied thereto, said free end being located inwardly of the pivot means of said fuse tube assembly, whereby when said free end is forced downwardly said fuse tube assembly will tend to rock inwardly toward said support assembly and prevent premature separation of said movable upper contact from said stationary upper contact.

2. A dropout expulsion fuse construction comprising a support assembly having upper and lower stationary contacts; a fuse tube assembly including a fuse tube having trunnions adjacent its lower end pivotally supported from said support assembly and having upper and lower movable contacts normally engaging said upper and lower stationary contacts, said fuse tube being closed at its upper end and open at its lower end and having an open eyelet adjacent its upper end for the reception of the end of a switch stick for placing the fuse tube in service, a fuse link in said fuse tube electrically connecting said mov' able contacts and projecting from the open lower end of said fuse tube, means controlled by said fuse link for normally holding said fuse tube in position and causing disengagement of said upper movable and stationary contacts for downward and outward rocking motion of said fuse tube assembly upon rupture of said fuse link, and an operating lever pivoted at a fixed point on said fuse tube assembly and having a free, force-receiving end located inwardly of said trunnions with reference to said support assembly and operatively mechanically connected to said fuse link for mechanically rupturing said fuse link when a downwardly directed force is applied to the free, force-receiving end of said lever.

3. A dropout expulsion fuse construction comprising a support assembly having upper and lower stationary contacts; a fuse tube assembly comprising a fuse tube closed at its upper end and open at its lower end and having upper and lower movable contacts normally engaging said upper and lower stationary contacts and pivoted at a point on said support assembly adjacent the lower end of said fuse tube assembly, a fuse link in said fuse tube electrically connecting said upper and lower movable contacts and extending from the lower open end of said fuse tube, a fuse link extracting member pivoted on the lower portion of said fuse tube assembly and pivoted rearward ly of said fuse tube on said support assembly and corn trolled by said fuse link, and an operating arm pivoted on said fuse tube assembly for moving said fuse link extracting member downwardly to mechanically rupture said fuse link, force multiplying means between said operating arm and said fuse link extracting member for moving said operating member when said operating arm is rocked downwardly, said operating arm having a force receiving portion located rearwardly of the point at which said fuse link extracting member is pivoted on said support assembly for receiving a downwardly directed force.

4. A dropout expulsion fuse construction comprising a support assembly having upper and lower stationary contacts; a fuse tube assembly comprising a fuse tube closed at its upper end and open at its lower end and having upper and lower movable contacts normally engaging said upper and lower stationary contacts, a fuse link extracting and fuse tube supporting member pivoted on the lower portion of said fuse tube assembly and having rearwardly located trunnions pivotally supported from said support assembly, said fuse link extracting and fuse tube supporting member being controlled by said fuse link and normally holding said fuse tube in service position, and an operating arm pivoted on said fuse tube assembly and having force multiplying cam means engaging said fuse link extracting and fuse tube supporting member when said operating arm is rocked downwardly, said fuse link extracting and fuse tube supporting member being free to move independently of said operating arm, said operating arm having a rearwardly projecting part provided with a force receiving portion located rearwardly of said trunnions with respect to said support assembly for receiving a downwardly directed force.

5. A dropout expulsion fuse construction comprising a support assembly having upper and lower stationary contacts; a fuse tube assembly comprising a fuse tube closed at its upper end and open at its lower end and having upper and lower movable contacts normally engaging said upper and lower stationary contacts, a fuse link extracting member pivoted at a fixed point on the lower portion of said fuse tube assembly and having rearwardly located trunnions pivotally supported from said support assembly, said fuse link extracting member being controlled by said fuse link and normally holding said fuse tube in service position, and an operating arm pivoted at a fixed point on said fuse tube assembly and having force multiplying means engaging said fuse link extracting member and having a rearwardly projecting arm provided with a force receiving portion located rearwardly of said trunnions with respect to said support assembly said operating arm being spaced from the open bottom end of said fuse tube and out of the path of gases expelled from the open bottom end of said fuse tube upon rupture of said fuse link.

6. An expulsion fuse construction comprising a support assembly having upper and lower stationary contacts: a fuse tube assembly including a fuse tube pivotally sup ported from said support assembly and having upper and lower movable contacts normally engaging said upper and lower stationary contacts, said fuse tube being arranged for opening rotative movement outwardly from said support assembly, said fuse tube having an open eyelet adjacent its upper end for the reception of a switch stick for rocking the fuse tube into service position, the open portion of said eyelet being directed outwardly towards the opening rotative movement of said fuse tube, a fuse link in said fuse tube electrically connecting said upper and lower movable contacts, and an operating lever pivotally supported on said fuse tube assembly and having a free, force-receiving end located inwardly of the point at which said fuse tube assembly is pivoted on said support assembly and operatively mechanically connected to said fuse link for mechanically rupturing said fuse link when a downwardly directed force is applied to the free, forcereceiving end of said lever.

References Cited in the file of this patent UNITED STATES PATENTS 973,613 Atwood Oct. 25, 1910 2,081,623 Fox May 25, 1937 2,172,143 Lemmon Sept. 5, 1939 2,310,466 Schultz et al. Feb. 9, 1943 2,400,850 Steinmayer et al. May 21, 1946 2,514,163 Pittman July 4, 1950 2,630,508 Meisenheimer et al. Mar. 3, 1953 2,680,171 Curtis et al. June 1, 1954 2,737,551 Curtis et al. Mar. 6, 1956 

